The background experience culminating in the optical techniques of the present invention stems from the inventor's pioneering work in firstly laser-particle physics (Nature--May 1963), secondly in laser radar, firstly at the Royal Radar Establishment, Malvern, UK (1963-64) then at the Weapons Research Establishment, Salisbury, South Australia under the auspices of the British-Australian Joint Projects Board. The early experiments on optical fibre transmission of laser light was carried out at the Royal Radar Establishment in 1963 with a view of developing advanced, fibre optic coupled laser radar systems rather than for optical communications networks. Unfortunately, the optical quality of optical fibres in those early days were not very good and scattering losses were very high. However, in laser radar transmitters it was not the scattering losses per se that was the problem rather the fact that the fibres then available were severely multimode and the coherent laser beam input was immediately distorted into an incoherent optical beam. However, advanced phased-array laser radars which emerged from these pioneering experiments at the Royal Radar Establishment in 1963 have one thing in common with optical communication systems, namely, their individual, sectionally doped optical fibre oscillator-amplifier links are virtually identical with the length of the doped section in the oscillators ranging from a few millimeters to a few centimeters whilst the length of the doped sections firing the amplifier can be up to ten meters. The fundamental difference between phased-array laser radar utilizing optical fibres and optical communications systems is that in the former the phased-locked optical fibre bundles are packed to one million per square centimeter of the radar's transmitting aperture whilst a single strand of optical fibre is adequate for an optical communications network link. In terms of optical techniques, both phased-array laser radar techniques and optical communications techniques are, to a great extent, interchangable so that this invention has benefited by the channelling of the extensive background experience associated with the developments of laser radar since 1963. Radio active pumping is an alternative to optical excitation of the doped sections of the fibres because of the relative low power requirements of the repeaters of the invention.